1. Field of the Invention
The invention concerns a fuel pump of a motor vehicle, in particular for diesel fuel with a pump stage provided for the induction of fuel from a fuel tank, with an electric motor for driving the pump stage and with control electronics for supplying the electric motor with electrical current. Furthermore, the invention concerns a method for operating a fuel pump of a motor vehicle, in particular for diesel fuel, with which control electronics supply an electric motor with electrical current and the electric motor drives a pump stage that sucks fuel from a fuel tank.
2. Related Art
With fuel pumps known from practice for diesel fuels, the pump stage is in the form of a displacement pump. An electrically commutated motor is mainly used as an electric motor. Such displacement pumps can, for example, be so-called G-rotor pumps, screw pumps or roller cell pumps. With these, in principle both the electric motors used and also the pump stages used have torque or load fluctuations with the angle of rotation. In order to ensure a reliable start of the internal combustion engine supplied by the fuel pump, with today's fuel pumps a pressure rise from zero to 4 to 6 bar is required in the start-up phase within 100 ms to 300 ms. Methods for operating such fuel pumps are generally designed to comply with emission values during the rapid pressure rise. Taking the viscosity of the fuel into account is not provided.
However, diesel fuel has the property that below a certain temperature paraffins are excreted as flakes. This results in increasing viscosity of the fuel with reducing temperature. Above a certain viscosity, the envisaged start-up of the fuel pump is therefore hindered, which results in a false start of the internal combustion engine supplied by the fuel pump.